The present invention relates to a wrench and more specifically to a ratchet wheel wrench.
In the prior art, such ratchet wheel wrenches comprise a ratchet wheel groove and a crescent groove communicating the ratchet wheel groove on the wrench head and a ratchet wheel is mounted in the ratchet wheel groove. A ratchet tooth support is provided in the crescent groove. One side of the ratchet tooth support and teeth engaged with the ratchet wheel while the other side of the ratchet tooth support leans against the side wall of the crescent groove. A cooperating block opposite the ratchet tooth support is located at the side of the crescent groove which leans against the side wall of the crescent groove. Two through holes are provided on corresponding surfaces of the cooperating block and the ratchet tooth support, respectively, in which there are springs inserted.
Such prior art ratchet wheel wrenches are not very convenient because the cooperating block is disposed in the crescent groove. In addition it is difficult and expensive to manufacture either by forging or by conventional welding. Furthermore, holes need to be provided by milling, for example, on the cooperating block and the ratchet tooth support. Hence, such wrenches are difficult and expensive to manufacture.
As disclosed on Chinese patent ZL200720108388.2, the cooperating block in the crescent groove is a magnetic cooperating block, fixing the spring by magnetism. This patent does not provide for milling holes into the cooperating block, while the cooperating block is not fixed firmly in the crescent groove so that the magnetism of the cooperating block may fade away and causing the spring to be ineffective.